mirror of
https://gitlab.com/camelot/kickc.git
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155 lines
3.7 KiB
NASM
155 lines
3.7 KiB
NASM
// NMI Sample Player using the SID volume register
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// Code by Scan of Desire (Richard-William Loerakker)
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// Sample from ART OF NOISE: MOMENTS IN LOVE
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// Commodore 64 PRG executable file
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.file [name="nmisamples.prg", type="prg", segments="Program"]
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.segmentdef Program [segments="Basic, Code, Data"]
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.segmentdef Basic [start=$0801]
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.segmentdef Code [start=$80d]
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.segmentdef Data [startAfter="Code"]
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.segment Basic
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:BasicUpstart(__start)
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/// Value that disables all CIA interrupts when stored to the CIA Interrupt registers
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.const CIA_INTERRUPT_CLEAR_ALL = $7f
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.const SAMPLE_SIZE = $6100
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.const OFFSET_STRUCT_MOS6526_CIA_INTERRUPT = $d
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.const OFFSET_STRUCT_MOS6526_CIA_TIMER_A = 4
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.const OFFSET_STRUCT_MOS6526_CIA_TIMER_A_CONTROL = $e
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.const OFFSET_STRUCT_MOS6569_VICII_BORDER_COLOR = $20
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.const OFFSET_STRUCT_MOS6581_SID_VOLUME_FILTER_MODE = $18
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/// The SID MOS 6581/8580
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.label SID = $d400
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/// The VIC-II MOS 6567/6569
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.label VICII = $d000
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/// The CIA#2: Serial bus, RS-232, VIC memory bank
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.label CIA2 = $dd00
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/// CIA#2 Interrupt for reading in ASM
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.label CIA2_INTERRUPT = $dd0d
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/// The vector used when the KERNAL serves NMI interrupts
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.label KERNEL_NMI = $318
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.label sample = 2
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.segment Code
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__start: {
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// char* volatile sample = SAMPLE
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lda #<SAMPLE
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sta.z sample
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lda #>SAMPLE
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sta.z sample+1
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jsr main
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rts
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}
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nmi2: {
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sta rega+1
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sty regy+1
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// (VICII->BORDER_COLOR)++;
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inc VICII+OFFSET_STRUCT_MOS6569_VICII_BORDER_COLOR
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// asm
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lda CIA2_INTERRUPT
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// *sample >> 4
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ldy #0
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lda (sample),y
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lsr
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lsr
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lsr
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lsr
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// SID->VOLUME_FILTER_MODE = *sample >> 4
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sta SID+OFFSET_STRUCT_MOS6581_SID_VOLUME_FILTER_MODE
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// sample++;
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inc.z sample
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bne !+
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inc.z sample+1
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!:
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// BYTE1(sample)
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lda.z sample+1
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// if (BYTE1(sample) == BYTE1(SAMPLE+$6100))
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cmp #>SAMPLE+$6100
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bne __b1
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// sample = SAMPLE
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lda #<SAMPLE
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sta.z sample
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lda #>SAMPLE
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sta.z sample+1
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__b1:
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// *KERNEL_NMI = &nmi
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lda #<nmi
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sta KERNEL_NMI
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lda #>nmi
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sta KERNEL_NMI+1
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// (VICII->BORDER_COLOR)--;
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dec VICII+OFFSET_STRUCT_MOS6569_VICII_BORDER_COLOR
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// }
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rega:
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lda #0
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regy:
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ldy #0
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rti
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}
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nmi: {
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sta rega+1
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sty regy+1
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// (VICII->BORDER_COLOR)++;
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inc VICII+OFFSET_STRUCT_MOS6569_VICII_BORDER_COLOR
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// asm
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lda CIA2_INTERRUPT
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// *sample & $0f
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lda #$f
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ldy #0
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and (sample),y
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// SID->VOLUME_FILTER_MODE = *sample & $0f
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sta SID+OFFSET_STRUCT_MOS6581_SID_VOLUME_FILTER_MODE
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// *KERNEL_NMI = &nmi2
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lda #<nmi2
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sta KERNEL_NMI
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lda #>nmi2
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sta KERNEL_NMI+1
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// (VICII->BORDER_COLOR)--;
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dec VICII+OFFSET_STRUCT_MOS6569_VICII_BORDER_COLOR
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// }
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rega:
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lda #0
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regy:
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ldy #0
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rti
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}
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main: {
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// asm
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// Boosting 8580 Digis
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// See https://gist.github.com/munshkr/30f35e39905e63876ff7 (line 909)
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lda #$ff
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sta $d406
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sta $d40d
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sta $d414
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lda #$49
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sta $d404
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sta $d40b
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sta $d412
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sei
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// CIA2->INTERRUPT = CIA_INTERRUPT_CLEAR_ALL
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lda #CIA_INTERRUPT_CLEAR_ALL
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sta CIA2+OFFSET_STRUCT_MOS6526_CIA_INTERRUPT
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// *KERNEL_NMI = &nmi
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lda #<nmi
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sta KERNEL_NMI
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lda #>nmi
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sta KERNEL_NMI+1
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// CIA2->TIMER_A = 0x88
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lda #<$88
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sta CIA2+OFFSET_STRUCT_MOS6526_CIA_TIMER_A
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lda #>$88
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sta CIA2+OFFSET_STRUCT_MOS6526_CIA_TIMER_A+1
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// CIA2->INTERRUPT = 0x81
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// speed
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lda #$81
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sta CIA2+OFFSET_STRUCT_MOS6526_CIA_INTERRUPT
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// CIA2->TIMER_A_CONTROL = 0x01
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lda #1
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sta CIA2+OFFSET_STRUCT_MOS6526_CIA_TIMER_A_CONTROL
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// asm
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cli
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// }
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rts
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}
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.segment Data
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SAMPLE:
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.import binary "moments_sample.bin"
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